1. Technical Field
The present disclosure relates to a display panel and, more particularly, to a display panel improving a pressure resistance and a liquid crystal drip margin by improving a structure of a column spacer maintaining a space between both display panels.
2. Discussion of Related Art
A display panel is used in a display device to display images. There are various kinds of display panels such as a liquid crystal display (LCD), which is a type of flat panel display for displaying images using liquid crystals. In general, LCDs feature low power consumption, slim, lightweight design, with low driving voltage.
A conventional liquid crystal panel includes an upper substrate having common electrodes and color filters, a lower substrate having thin film transistors and pixel electrodes, a liquid crystal layer between the upper and lower substrates, and a spacer for maintaining a space between the opposing substrates. An LCD displays images by applying electric potentials to the pixel electrodes and the common electrodes to generate an electric field in the liquid crystal layer to control the alignment of the liquid crystal molecules and the quantity of light transmitted.
To improve the display quality of an LCD device, the uniformity of the thickness of the liquid crystal layer (also referred to as the “cell gap” or “cell thickness”) can be controlled. The cell gap is controlled by spacers disposed on the upper and lower substrates. The common types of spacers include spherical silica bead spacers that are randomly arranged, and column spacers or rigid spacers formed in a regular pattern.
The column spacers may be formed in a desired pattern corresponding to an area outside the emissive region of pixels, for example, at a channel portion, a gate line, or a storage electrode line, using standard photolithography techniques.
A conventional column spacer may be formed approximating a shape of a cylinder, a truncated circular cone, or a hemisphere. A cross-section of the conventional column spacer parallel to the surface of the display panel may approximate a shape of a circle, an ellipse, a quadrangle, or a rhombus.
However, external pressure may be applied to the display panel during the manufacturing process thereof or during use. When the conventional column spacers are used to maintain a space between the opposing substrates, the column spacers may become deformed or collapse because of external pressure, or a lower layer of the column may collapse. This may cause cell gap non-uniformity in the display panel. The thickness and uniformity of the cell gap affects display performance. If the cell gap non-uniformity occurs, color irregularity may occur.
The liquid crystal material may be drip-fed on the surface of one substrate, on which a closed pattern is formed with a sealing material, so that a filler hole for injection need not be provided, but if the number of the column spacers is increased to improve the pressure resistance characteristic, a liquid crystal drip margin is deteriorated.